Reproducibility of the surveillance effect to decrease nosocomial infection rates

OBJECTIVE

To investigate whether the reduction effect due to participation in a nosocomial infection surveillance system for laboratory-confirmed central venous catheter (CVC)-associated primary bloodstream infection (BSI), ventilator-associated pneumonia (VAP), and surgical site infection (SSI) is reproducible for different time periods, independent of confounding factors that might occur during a specific time period.

METHODS

Data from the German national nosocomial infection surveillance system from the period January 1997 through June 2008 were used. CVC-associated BSI data and SSI data were analyzed for 3 starting periods, and VAP data were analyzed for 2 starting periods. Monthly infection rates were calculated for the following 36 months, and relative risks comparing the first and third surveillance years of each period were calculated.

RESULTS

A total of 2,399 CVC-associated BSI cases from 267 intensive care units, 3,637 VAP cases from 150 intensive care units, and 829 SSIs following 3 different procedures from 113 departments were analyzed. A significant reduction in VAP was shown for both starting periods investigated (overall relative risk [RR], 0.80 [95% CI, 0.74-0.86]). A significant reduction in CVC-associated BSI was demonstrated for 2 of 3 starting periods (overall RR, 0.83 [95% CI, 0.75-0.91]). A significant reduction in SSI was found for 2 starting periods for knee prosthesis insertion (overall RR, 0.56 [95% CI, 0.38-0.82]), for all of the 3 starting periods for cesarean delivery (overall RR, 0.75 [95% CI, 0.61-0.93]), and for none of the 3 starting periods for endoscopically performed cholecystectomy (overall RR, 0.89 [95% CI, 0.62-1.27]).

CONCLUSIONS

The surveillance effect, manifest as a significant reduction of nosocomial infection rates between the first and third years of participation in a surveillance system, was observed independently from the calendar year in which the surveillance activities started.

Impact of a change in antibiotic prophylaxis on total antibiotic use in a surgical intensive care unit

OBJECTIVE

The aim of this study was to evaluate the impact of reducing the length of antibiotic prophylaxis for cerebro spinal shunts on total antibiotic use and key resistant pathogens.

METHODS

In January 2004, the use of antibiotic prophylaxis was reduced to a single shot dose with cefuroxime in an intensive care unit (ICU). Prior to this intervention, prophylaxis with second-generation cephalosporins was administered during the entire period of external cerebro spinal fluid (CSF) drainage. The effect on the antibiotic use density (AD: DDD [defined daily doses] per 1,000 patient-days[pd]) was calculated prior to (January 2002-December 2003) and following implementation of the intervention(January 2004-December 2006) by segmented regression analysis of an interrupted time series. Resistance proportions(RP) and resistance densities (RD), defined as resistant pathogen/1,000 pd of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecalis or E. faecium, third-generation-resistant (3GC) Escherichia coli and Klebsiella pneumoniae, and imipenem-resistant Pseudomonus aeruginosa, were compared by the Fisher's exact test before and after the intervention.

RESULTS

Total antibiotic use by 147 DDD/1,000 pd decreased after the intervention when pre-operative prophylaxis was changed into single shot prophylaxis, from an estimated mean of 1,036 DDD/1,000 pd before the intervention to 887DDD/1,000 pd post-intervention. This decrease was primarily due to a significant reduction in the amount of cefuroxime used for prophylaxis. The reduction in total antibiotic consumption was sustainable, and it did not increase again during the next 36 months. The RR and RD of third-generation cephalosporin-resistant E. coli increased after January 2004, whereas the percentage of MRSA significantly decreased.

CONCLUSION

Change to single shot prophylaxis along with an ongoing antibiotic stewardship program resulted in a cut-back in total antibiotic use amounting to as much as 15%. It would therefore appear that targeting interventions aimed at reducing antibiotic prophylaxis in surgical ICUs may be very worthwhile.

[Surveillance of antibiotic use and bacterial resistance in intensive care units]

SARI (Surveillance of Antibiotic Use and Bacterial Resistance in Intensive Care Units) provides data on antibiotic use, resistance rates (RR) and resistance densities (RD) in 47 interdisciplinary, medical and surgical intensive care units in Germany. Mean total antibiotic use was 1170 defined daily doses per 1000 patient days (pd). RD of MRSA has remained stable since 2001 in contrast to a continuous increase in the RD of 3rd generation cephalosporins E. coli (4.3 and 1.4, respectively, resistant pathogens/1000 pd in 2007). Local data of antibiotic use and bacterial resistance are important for the antibiotic and quality management of the individual ICUs. Pooled data of antibiotic use and bacterial resistance allow trends and extrapolations for Germany, which are relevant for future strategies.

Costs of nosocomial Clostridium difficile-associated diarrhoea

Nosocomial Clostridium difficile-associated disease (CDAD) is a common infection in hospitals. A matched case-control study was carried out to determine hospital-wide excess costs due to CDAD. Cases were assessed by prospective hospital-wide surveillance in a tertiary care university hospital in 2006. Nosocomial cases of CDAD (>72h after admission) were matched to control patients without CDAD in a ratio 1:3 using the same diagnosis-related group in the same year, for a hospital stay at least as long as the time of risk of the CDAD cases before infection and a Charlson comorbidity index +/-1. Data on overall costs per case were provided by the finance department. Matching was possible for 45 nosocomial CDAD cases. The difference in the length of stay showed that CDAD cases stayed significantly longer (median 7 days; P=0.006) than their matched controls. The average cost per CDAD patient was euro 33,840. The difference in the cost per patient showed that the cost for CDAD patients was significantly more than for their matched controls (median euro 7,147; 95% confidence interval: 4,067-9,276). Nosocomial CDAD is associated with high costs for healthcare systems. Clinicians should be aware of the financial impact of this disease and the application of appropriate infection control measures is recommended to reduce spread.

Incidence of healthcare-associated infections in high-risk neonates: results from the German surveillance system for very-low-birthweight infants

Infants with birthweight <1500g (VLBW) are at high risk of healthcare-associated infection (HAI). We present surveillance data from the NEO-KISS surveillance system, collected between 2000 and 2005 by 52 neonatology departments in Germany. Infants were stratified into two birthweight categories (<1000 and 1000-1499 g), and rates of nosocomial bloodstream infection (BSI), nosocomial pneumonia and necrotising enterocolitis (NEC) were calculated. The data presented comprise 8677 VLBW and 339,972 patient-days. The incidence of bloodstream infection was 6.5 per 1000 patient-days (8.5 and 4.0 according to birthweight category). The incidence of central venous catheter (CVC)-associated BSI was 11.1 per 1000 CVC-days and the incidence of peripheral venous catheter (PVC)-associated BSI was 7.8 per 1000 PVC-days. The incidence of pneumonia was 0.9 per 1000 patient-days (1.3 and 0.4 according to birthweight category). The incidence of pneumonia among intubated patients was 2.7 per 1000 ventilator-days, while the incidence of pneumonia among patients receiving continuous nasel positive airway pressure (CPAP) was 1.0 per 1000 CPAP-days. The incidence of NEC was 0.9 per 1000 patient-days (1.1 and 0.6 according to birthweight category). HAI is frequent among VLBW and shows wide variation between neonatology departments. Preventive strategies to reduce infections in these infants should be prioritised.

Surveillance of antimicrobial use and antimicrobial resistance in German intensive care units (SARI): a summary of the data from 2001 through 2004

Objective:

To report the experience gained over 4 years in working with the German SARI project (Surveillance of Antimicrobial Use and Antimicrobial Resistance in Intensive Care Units), and to compare SARI with data from the Swedish STRAMA and the US AUR surveillance system.

Methods:

Prospective unit and laboratory based surveillance was carried out in 40 German ICUs from 2001 through 2004. WHO 2004 definitions of defined daily doses (DDD) per 1,000 patient days (pd) were used to express antimicrobial consumption (AD). Apart from the proportion of resistant isolates (RP), the incidence density of resistant isolates (RD) was calculated on the basis of the number of resistant isolates per 1,000 pd. To determine the changes over time, the Wilcoxon signed rank test for paired samples was used.

Results:

From 1/2001 through 12/2004, 40 ICUs provided data on 53,399 isolates, a total of 789,569 DDD and 597,592 pd. Total AD ranged from 427 to 2,798, with the median being 1,351. There was no statistically significant change in total antimicrobial use, but a statistically significant decrease was observed in the use of aminoglycosides. RD was highest for MRSA with 4.4 resistant isolates/1,000 pd followed by imipenem resistant Pseudomonas aeruginosa with 1.7 resistant isolates/1,000 pd. The corresponding RPs were 21.5% and 23.2%. Over the 4-year period (2001–2004), significant increases were seen in the RDs of third generation cephalosporin and ciprofloxacin resistant Escherichia coli. In 2004, the mean RD reached 0.28 and 1.41, respectively. In comparison, the RP of selected pathogens was highest in the US ICUs and lowest in Swedish ICUs, with the exception of imipenem resistant P. aeruginosa.

Conclusion:

Antibiotic consumption remained stable over a period of 4 years, (the mean being 1,321 DDD/1,000 pd). The same applied to the situation regarding resistance in Staphylococcus aureus, enterococci and P. aeruginosa. For most pathogens the RP was higher in SARI ICUs than in Swedish ICUs, but lower than in US ICUs.

Different trends of MRSA and VRE in a German hospital, 1999-2005

Some of the clinically most menacing nosocomial pathogens are Methicillin-resistent Staphylococcus aureus (MRSA) and Vancomycin-resistent Enterococcus (VRE). During the last years both pathogens showed dramatic increases in colonization and infection rates in Germany. This study covers all patients positively tested for MRSA and VRE in a German University Hospital from 1999-2005. About 1,179 MRSA cases and 116 VRE cases have been reported. VRE was significantly associated with less infection, female gender, more death and higher nosocomial acquisition than MRSA. While MRSA rates increased impressively from 1999 to 2005 VRE rates decreased clearly. Assuming that compliance with hygienic measures is similar in dealing with MRSA and VRE it is quite unclear why these two major pathogens differ so much in their trends. One possibility is that the MRSA problem has been caused by an increasing share of nonnosocomially acquired MRSA.

Reducing neonatal nosocomial bloodstream infections through participation in a national surveillance system

A national nosocomial surveillance system for neonatal intensive care patients with a very low birthweight was set up in Germany in 2000 (NEO-KISS). Forty-eight neonatal intensive care units (NICUs) participated in the programme, which focused upon nosocomial bloodstream infections (BSIs) and pneumonia. Only data from NICUs participating for at least three years were included and the years compared. The relative risks and their 95% confidence intervals (CIs) were calculated and a multiple logistic regression analysis performed to identify significant risk factors. Twenty-four units that met the selection criteria accumulated data for 3856 patients and 152 437 patient-days in their first three years of participation. The incidence density of BSIs decreased significantly by 24% from 8.3 BSIs per 1000 patient-days in the first year to 6.4 in the third year. In the multiple logistic regression analysis, BSI in the third year of participation was significantly lower than in the first year of participation (odds ratio=0.73, 95% CI 0.60-0.89). The year of participation was an independent risk factor for BSI but not for pneumonia. Our data suggest that participation in ongoing surveillance of nosocomial infections in NICUs, requiring individual units to feedback data, may lead to a reduction in BSI rates.

Stenotrophomonas maltophilia and antibiotic use in German intensive care units: data from Project SARI (Surveillance of Antimicrobial Use and Antimicrobial Resistance in German Intensive Care Units)

Risk factors for the selection of Stenotrophomonas maltophilia were analysed by correlating antimicrobial use and structure parameters (e.g. hospital type) with the incidence density of S. maltophilia and the percentage of S. maltophilia isolated from 39 intensive care units (ICUs). SARI (Surveillance of Antimicrobial Use and Antimicrobial Resistance in German Intensive Care Units) is a prospective unit- and laboratory-based surveillance system that collects data on the 13 most important organisms responsible for nosocomial infections. The percentage of S. maltophilia among these organisms and the number of S. maltophilia per 1000 patient-days were calculated. The data were subsequently correlated with antibiotic use density calculated in defined daily doses (DDDs) per 1000 patient-days and structure parameters. The data covered a total of 28 266 isolates and 431 351 DDDs. The antibiotic use density ranged from 427 to 2218, with the median being 1346. Over the two-year period, the median of S. maltophilia per 1000 patient-days was 1.4 (range 0-7.6). Calculation of antibiotic use and S. maltophilia per 1000 patient-days showed a significant positive correlation with the use of carbapenems, ceftazidime, glycopeptides and fluoroquinolones, as well as with total antibiotic use. In the multiple logistic regression analysis, carbapenem use and >12 ICU beds were independently and positively associated with a high number of S. maltophilia per 1000 patient-days. Benchmarking data provided for incidence densities of S. maltophilia in ICUs revealed the heterogeneous situation of the burden of S. maltophilia in individual ICUs. The multi-centre data showed that carbapenem use and >12 ICU beds were independent risk factors for the isolation of S. maltophilia.